[U-Boot] [PATCH V2] README: document the requirements for CONFIG_SYS_HZ

[Stephen Warren]

CONFIG_SYS_HZ must be 1000, and get_timer() must therefore return ms.
Document this.

README text provided by Tom Rini.

Signed-off-by: Stephen Warren <swarren at wwwdotorg.org>
---
v2: Reworded the README text.
---
 README |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/README b/README
index 7f2506a..efb8cc6 100644
--- a/README
+++ b/README
@@ -495,6 +495,13 @@ The following options need to be configured:
 		exists, unlike the similar options in the Linux kernel. Do not
 		set these options unless they apply!
 
+- CPU timer options:
+		CONFIG_SYS_HZ
+
+		The frequency of the timer returned by get_timer().
+		get_timer() must operate in milliseconds and this CONFIG
+		option must be set to 1000.
+
 - Linux Kernel Interface:
 		CONFIG_CLOCKS_IN_MHZ
 
-- 
1.7.10.4